Streamlined antenna and method of making the same



1968 E. A. EDWARDS Em 3,419,876

STREAMLINED ANTENNA AND METHOD OF MAKING THE SAME Fil ed Aug. 26. 1964 'INVENTOR. I

BY )h.

ATTORNEYS United States Patent STREAMLINED ANTENNA AND METHOD OF MAKENG THE SAME Eugene A. Edwards, Cleveland Heights, and George M. Winterstein, Cleveland, Ohio, assignors to Tenatromcs LttL, Inc., Cleveland, Ohio, a corporation of Ohio Filed Aug. 26, 1964, Ser. No. 392,195 7 Claims. ((31. ($43-$01) This invention relates to telescopic antennas for automobiles and other vehicles and to methods of making them. More particularly, this invention relates to the method of making, as well as the structure of, telescopic automobile antennas in which the several sections are contoured to minimize the wind noise and air-drag on the antennas when the automobiles are driven at high speeds.

Heretofore telescopic automobile antennas have been assemblies of cylindrical tubing surrounding a central cylindrical rod or tube of relatively small diameter. The wind noise of such conventioned antennas, when raised, can be a substantial factor in the noise level heard in convertibles driven at high speeds and automotive engineers have been seeking antennas which would minimize such external noise, both for convertibles and also even for closed cars which can be more easily sound-proofed. The air-drag at high speeds on a conventional cylindrical telescopic antenna, while a negligible factor as far as its load on the power of the car is concerned, is functionally objectionable in that it can cause the antenna to bend down; to a degree such bending due to air-drag lessens the effective height of the antenna and thereby impairs radio reception from distant stations. The principal objection to such bending due to air drag (which most antennas are designed to undergo without harm) is, however, the psychological one of alarming the occupants of cars who see the antennas bend and whip at high speeds.

It has long been obvious that wind noise and drag on telescopic automobile antennas could be minimized if the conventional cylindrical cross-section could be changed to a tear-drop section and thereby streamline the antenna. So far the art has progressed to this end by utilizing a lowermost section of tubing enshrouded, extruded, or rolled into the obvious tear-drop shape. The upper end of this tear-drop shaped lowermost section is provided with a relatively expensive die-cast fitting through which an assembly of a conventional cylindrical intermediate section or sections and a central cylindrical rod may be collapsed into the lowermost section,

the die casting closing the opening which would otherwise be left between the upper end of the lowermost section and the remaining sections collapsible therein. This attempted solution was objectionable for several reasons: First, it had no effect on reducing the noise created by the more flexible upper sections which, when raised, are the principal source of noise; second, due to the radical step-up in stiffness from the lowermost streamlined section and the next adjacent cylindrical section of smaller diameter, rather than the more gradual step-up in conventional telescopic antennas, permanent bends or breaks in the upper sections could result; third, the nonstardard shape of the tubing used for the lowermost section and the die casting used at its upper end are relatively expensive and increase the cost of the antenna.

The reason the art could only progress to the stage of providing a streamlined shape for the lowermost section of a telescopic automobile antenna was due to the obstacle presented by a seemingly minor but very necessary requirement in the manufacture and sale of telescopic antennas. The lower ends of each telescoping section of an antenna must be provided with flexible 3,419,875 Patented Dec. 31, 1968 contacts which carry sharp points engaging the inner diameter of the surrounding tube into which the section telescopes; this is necessary to insure constant electrical contact between the sections and eliminates the electrical noise which will be created in the receiver, if they are absent, due to mechanical vibrations of the sections with respect to each other. The need for such contacts requires that there be a clearance for them between the section which carries the contacts and the surrounding tube. Unless this inside clearance between sections is fully packed with grease or like viscous fluid when the antenna is collapsed, the antenna will so mechanically rattle that it will be unacceptable to a public which has long been used to non-rattling antennas. To retain such rattlesuppressing grease within an antenna and maintain its acceptability, each tubular section of a telescopic antenna section must carry tight packing which prevents the grease from escaping as the antenna is raised and lowered. The problem of providing, except at completely prohibitive cost, both a packing and a retaining means therefor which would effectively prevent grease from escaping around a non-cylindrical section and its surrounding tube was, therefore, the obstacle which, heretofore, restricted art from providing streamlined shapes for a telescopic antenna in any section other than the lowermost.

It is an object and advantage of this invention, therefore, not only to provide a telescopic antenna which is contoured to provide streamlined shapes in all of its sections, thereby reducing wind noise and air-drag, but which may be economically produced with seals and retaining means therefor which retain sound-deadening grease between the non-cylindrical, streamlined sections as they are raised and lowered. Another advantage of this invention is that antennas embodying the structure and made according to the method of this invention not only reduce air-drag on the antenna when fully raised but, when mounted so as to present their minimum frontal area to the direction of travel, they are stilfer and less inclined to bend or whip in that direction. Further, while antennas made according to this invention are flexible in a direction transverse to the normal direction of travel, they may be made with gradual step-downs in flexibility between sections and, therefore, may be made to withstand substantial flexing without permanent bends or breaks.

The foregoing and additional objects, features, and advantages of the invention will become apparent and more fully understood from the following detailed description of the invention, claims, and the accompanying drawings, in which:

FIGURE 1 is a fragmentary, perspective view, partly broken away and with wall thicknesses somewhat exaggerated for clarity, of an antenna embodying the invention;

FIGURE 2 is a sectional view of the antenna, the plane of the second being indicated by the line 22 in FIG- URE 1;

FIGURE 3 is a sectional view of the antenna, the plane of the section being indicated by the line 33 in FIG- URE 1;

FIGURE 4 is a sectional view of the antenna, the plane of the section being indicated by the line 44 in FIG- URE 1;

FIGURE 5 is a cross-sectional view of a portion of an antenna, illustrating a manufacturing operation;

FIGURE 6 is a sectional view of an antenna which is similar to FIGURE 5, but which illustrates a later manufacturing operation;

FIGURE 7 is a sectional view similar to FIGURES 5 ang 6, but showing a still later manufacturing operation; an

FIGURE 8 is a plan view of the antenna portion illustrated in FIGURE 7.

Referring now to the drawings, and particularly to FIGURES 1 through 4, a raised telescopic antenna is illustrated. The antenna 10 comprises a mounting fitting 11, a tubular lowermost section 12, a tubular intermediate section 13, and a top rod section 14.

The top section 14 is usually a solid rod carrying an upper ornamental finial 24 provided at its lower end with a leaf spring 15 spot welded or otherwise secured at its upper end to the rod 14. The leaf or leaves of the spring 15 are biased to extend outwardly from the bottom of the rod 14 so that the raised contact points 16 on the spring 15 will bear against and maintain electrical contact with the inner wall surface of the intermediate tubular section 13 while permitting the sound-deadening grease or fluid (not shown) to flow around the spring 15 as the top section 14 is telescoped in and out of the tubular section 13. It is to be understood, of course, that in this and other sections telescopically received in a concentric tube, means other than leaf-spring means may be employed at the lower end of the section to maintain constant electrical contact; for example, the lower end of the section may be split and spread so as to provide a resilient contact.

It is to be noted that the top rod section 14 has a symmetrical bi-convex cross-section which is essentially lenticular so that, when the antenna 10 is mounted to present its major axis in fore-and-aft alignment with the direction of travel of the car, it will present slightly rounded but otherwise relatively fine entering edge and trailing edges minimizing the eddies of air around it as the car travels at high speeds and, thereby, minimizing the wind noise and air-drag, such as would be obtained with a cylindrical rod of equal cross-sectional area. Also, with the top section 14 so mounted, it has a greater depth of cross-section in the direction of the air-drag load imposed on it than would be presented by a cylindrical rod of equivalent cross-sectional area and, therefore, has a greatly reduced tendency to bend backward at a given speed, due to the combination of both the lesser drag and the greater stiffness.

The intermediate tubular section 13 is provided at its lower end with a sliding contact leaf spring 19 similar to the contact spring 15. The intermediate section 13 has a streamlined cross-section which is substantially similar to the cross-section of the upper section 14, the sections 13 and 14 being assembled and oriented so that they are concentric with their elongated major axes in substantial alignment and the outer peripheries of their cross-sections are substantially equidistant.

It is to be noted that the upper end of the section 13 carries an internal packing 18 of polyethylene, nylon, or similar durable flexible material having an internal biconvex bore conforming to and closely fitting the rod section 14 under compression So as to seal in sound-deadening grease substantially filling the clearance between the section 14 and the section 13 when the antenna is collapsed. The internal packing 18 is retained against an internal shoulder provided by an elliptical counterbore in the upper end of the section 13 by means of a spun or swaged over-lip 17 on the tube 13. By being so retained, the packing 18 also serves as an internal stop; the top section 14 is prevented from being pulled out of the intermediate section 13 when the packing 18 is engaged by the upper end of the contact spring 15.

The lowermost tubular section 12 is of an elliptical cross-section having an internal elliptical bore receiving the section 13 carrying its leaf contact spring 19. The upper end of the section 12 carries an internal elliptical packing 21 similar to the packing 18, the packing 21 being held in compression against the outer surface of the section 13 by a lip crimped over the packing to hold the packing against an internal elliptical shoulder 23 formed on the inner wall of the section 12. The packing 21 thereby likewise serves as 'a stop preventing the section 13 from being pulled out of the section 12 when the spring contact 19 engages it in addition to its primary use as a retainer for the sound-deadening grease filling the clearance between the sections 12 and 13 when the antenna is collapsed.

The lower end of the section 12 is force-fitted or otherwise securely fixed in the base 11, which is provided with a lower cylindrical stem 25 by which the antenna may be mounted on an automobile body by means of substantially any conventional mounting bracket or fitting (not shown).

An economical method for making the above-described streamlined antenna is as follows:

The upper section 14 is preferably cut from a length of rod or wire rolled, drawn, or otherwise formed to provide the desired eddy-reducing cross-section; this crosssection may be the bi-convex lenticular section shown, an elliptical, oval or any other prolate cross-section providing a smooth periphery between the antennas entering edge or surface and its trailing edge or surface when the antenna is mounted so that the aligned major axes of its several sections are in a fore-and-aft direction on an automobile or other vehicle. The prolate cross-section of the antenna section 14 is preferably symmetrical about its major and transverse axes to provide simplicity in forming the wire or rod from which the section 14 is cut and in assembling and mounting the antenna. The prolate cross-section of the section 14 may be symmetrical about the major axes and asymmetric about its minor axis, e.g., oval, tear-drop, or pear shaped, or even asymmetric about both axes to provide a true air-foil section to control bending and modify the direction of such drag as does arise; such single or double asymmetry, however, essentially increases cost by requiring special and more expensive dies and may complicate assembly and installation.

After cutting the desired length of stock for the section 14, the contact spring 15 is secured to one end and the edge of the other end is preferably chamfered or tapered for assembly.

FIGURES 5 to 8 of the drawings are detailed showings at various stages of the manufacturing operations employed to form the lowest section 12 and provide it with a retained packing 21 having the requisite elliptical shape to serve as a grease seal around the intermediate section 13. As shown in FIGURE 5, a desired length of tubing 12' is cut from stock cylindrical tubing. The internal diameter of the tubing is selected so as to have a periphery substantially equal to the periphery or girth of the contact spring 19 around its contact points when the contact spring 19 is normally received and held in the section 12; the wall thickness of the tubing 12 is selected to permit its upper end to be counterbored with an end mill cutter to provide an internal shoulder 23, as shown in FIG. 5, the depth of the counterbore 22 being sufiicient to leave a lip 20 after receiving a packing ring 21, preferably molded to provide internal corrugations serving as wiping surfaces, as shown. The innermost diameter or diameters of the packing ring 21 are selected so that its unstressed periphery will be slightly less than the external periphery of the section 13 above the contact spring 19; thus, the packing will be under suflicient compression when it surrounds the section 13 to seal grease or other sound-deadening material in the clearance between the assembled sections 12 and 13.

Following assembly of the packing ring 21 within counterbore 22 of the length of cylindrical tubing 12', as shown in FIGURE 5, the lip 20 is then swaged, spun, or otherwise crimped inwardly to the position as shown in FIGURE 6 to lock the packing 21 in the upper end of the cylindrical tube 12'. The tube length 12 is placed in suitable forming and sizing dies, which are then closed to form the cylindrical assembly as shown in FIGS. 7 and 8; FIG. 8 being a bottom end view showing how the flexible cylindrical packing ring 21 assumes the desired elliptical shape for engaging the periphery of the section 13 while leaving an internal shoulder which acts as an outward stop engageable by the contact spring 19.

The section 13 is made by cutting a desired length from stock cylindrical tubing having an internal diameter selected to accomodate the next upper section to be received in it and a wall thickness suflicient to permit the packing ring 18 to be secured in its upper end in the same manner that the packing ring 21 is secured in the tubing 12'. The elliptical section 13 is then formed from such a cylindrical assembly by means of forming and sizing dies in the same manner that the section 12 is formed.

The sections 12 and 13 are shown as formed to elliptical shapes since such shapes have a prolate cross-section which can be obtained from cylindrical tubing with relatively inexpensive and simple forming dies and, at the same time, provide a streamlined antenna for the section which is as nearly eflicient, if not equally efficient, as any other section, insofar as effective reduction of wind noise and air-drag is concerned. The lowest section 12 and one or more intermediate sections 13 may, of course, have a lenticular, oval, pear-shaped, tear-drop, or air-foil crosssection, similar to the range of suitable cross-sections for the section 14, if the desire for an appearance, a selling point, or a product identification, attributable to such non-elliptical prolate shape warrants the cost of the dies for such alternate shapes.

The advantage of forming the tubular sections 12 and 13 from cylindrical malleable metal tubings, as described above, is not only that standard and relatively inexpensive tubings may be used but that standard cylindrical molded flexible packing rings may be used; further, standard tooling may be used for securing the packing rings in the sections prior to forming the tubings and packings to the desired prolate shapes in which the telescopic sections each have a smooth exterior surface whose longitudinal elements are parallel (except where each section is altered at one end to secure packing at that end). It is to be understood, of course, that instead of counterboring one end of a length of cylindrical tubing to provide a shoulder upon which a packing ring may be seated, other standard operations to provide such a seat and secure a packing in one end of a cylindrical tube may be used, such as, for example, internal grooving to receive an internal snapring or a snap-in packing. In short, the key to the sectionforming operation is to employ deformable cylindrical tubing and packing means which, after assembly into a section, may be shaped to provide the desired constant prolate cross-section throughout the telescoping portion of the antenna section.

With each section formed, the several sections are assembled by inserting each telescoping section upwardly into a surrounding section until it extends thereabove. In this connection, it should be noted that the inwardly crimped lip 17 of the intermediate section 13 provides a smooth appearance for the terminal portion of the section While serving as a retainer for the packing ring 18; this lip also serves as a reduced entering edge permitting insertion of the section 13 through the section 12 to place the packing 21 under compression without danger of dislodging it from the section 12. Thus, for the same operation of assembly and placing the packing ring 18 under compression, the upper edge of the section 14 is preferably chamfered.

After the sections 12, 13, and 14 are assembled, the ornamental finial 24 is force-fitted or otherwise secured on the upper end of the section 14, the assembly is filled with sound-deadening material, collapsed, and the base 11 is then secured to the bottom of the section 11 to complete the unit.

The foregoing is a detailed description of a preferred embodiment of this invention, which those skilled in the art may vary while utilizing the invention as defined in the following claims.

What is claimed is:

1. The method of making a telescopic antenna section having a prolate cross-section to permit lessened wind noise and air-drag at high speed comprising the steps of obtaining a length of cylindrical malleable tubing having the desired length for the section, securing an internal flexible packing having an internal cylindrical diameter less than the internal diameter of said tubing within said tubing adjacent one end thereof, and then compressing said tubing, and then compressing said tubing along its length until said tubing is formed to the desired prolate shape.

2. The method of making a telescopic antenna section as defined in claim 1 in which said packing is a ring having an external diameter greater than the internal and less than the external diameter of said tubing and in which the step of securing said packing ring in said tube includes the steps of forming in said tubing a socket of greater axial length than the length of said packing ring, inserting said packing ring in said socket, and forming an inward projection in the socket portion of said tubing to restrain said packing ring therein, and in which said tubing is of metal having suflicient strength in said socket portion to support and hold said packing ring in the desired prolate shape after formation of the tube to said shape.

3. The method of making a sectional telescopic antenna having a prolate cross-section including the steps of obtaining a length of electrically conductive rod or tubing having the desired prolate cross-section for the central upper section of the antenna, providing spring contact means on a lower end of said upper section, forming an adjacent prolate tubular section by obtaining a length of cylindrical malleable tubing having the desired length for the section, securing, within said tubing adjacent one end thereof, an internal flexible packing having an internal cylindrical diameter less than the internal diameter of said tubing, and then compressing said tube along its length until said tubing is formed to the desired prolate shape, internal maximum and minimum diameters of said adjacent prolate tubing being sufficient to receive said upper section with said contacts in a compressed condition and the internal circumference of said flexible packing engages the upper section above its contacts with a sealing engagement permitting sliding movement of said upper section therethrough, inserting the upper end of said upper section first into the lower end of said adjacent tubular section opposite said packing ring and then through said ring, injecting sufiicient vicous anti-rattling material in said adjacent prolate tubing to substantially fill the void between said upper section and adjacent tubing when said upper section is telescoped in said adjacent section, and closing the lower end of said adjacent section.

4. The method of making an antenna having at least three telescopic sections, each having a prolate cross-section, including the steps defined in claim 3 in which the step of closing the lower end of said adjacent section includes forming at least one additional section of prolate metal tubing according to the foregoing method by which the first prolate section adjacent the central upper section is formed and in which each additional section is provided with a flexible packing ring having an internal circumference which will engage the next inwardly adjacent prolate tubular section in a sealing engagement, providing spring contacts on the end of the tubular section adjacent the upper section and on the end of any additional prolate tubular section other than the section to become the lowest section of the telescopic antenna, assembling any additional prolate tubular sections in a telescopic arrangement on said tubular section next adjacent said upper section, injecting an adidtional viscous anti-rattling material necessary to substantially fill any voids left when the assembled sections are fully telescoped, and then closing the end of the lowermost prolate tubular section.

5. The method as defined in claim 4 in which outwardly successive tubular sections are shorter than the next inwardly adjacent section to prevent any inner section from being fully telescoped within its next adjacent outer section.

6. A telescopic antenna in which at least two adjacent telescopic sections each have a prolate cross-section comprising a first inner section having a prolate cross-section, a second adjacent tubular section having a prolate crosssection substantially corresponding in configuration to the cross-section of the adjacent inner section and telescopically assembled on said first section with the axes of said cross-sections in substantial alignment, a spring contact carried by said first section and secured adjacent the lower end thereof, the inner circumference of said second section being sufficiently larger than the outer circumference of said first section to receive said first carrying spring contact in a compressed condition, and a flexible packing ring carried by the upper end of said second section, said packing ring having an internal surface in sealing engagement with the surface of said first section above said contact, and a viscous anti-rattling material substantially filling the void between said first and second sections when telescoped to the minimum length of said antenna, whereby said packing ring seals said viscous material Within said antenna and serves as a stop limiting the maximum extension of said sections with respect to each other, and a mounting fixture closing the integral space in said antenna.

7. A telescopic antenna of more than two sections in which all sections have a prolate cross-section comprising a first inward section of a metallic rod having a susbtantially lenticular cross-section, a secon-d section of metal tubing having an elliptical cross-section, and a third tubular section of metal tubing having an elliptical cross-section, said sections all being telescopically assembled, spring contacts provided on the lower ends of each of the first and second sections, the internal diameters of the second and third section being only sufiiciently greater than the external diameters of the first and second sections, respectively, to receive said spring contacts in a compressed condition; each of said second and third sections being counterbored at their upper ends to provide a packing ring socket, normally circular flexible packing rings secured in said sockets by crimps in the upper ends thereof and distorted to a prolate shape by the prolate socket walls, a viscous oily liquid substantially filling internal voids between said sections when said antenna is telescoped, and a mounting fixture in which said outermost tubular section is secured and by which said liquid is retained in said antenna.

References Cited UNITED STATES PATENTS 1,236,617 1/1915 Stone 72367 1,915,699 6/1933 Squires 72-367 X 2,181,92'7 12/1939 Townsend 165-147 2,217,188 10/1940 Snyder 343-901 X 2,285,588 6/1942 Kirkes 343-901 X 2,481,823 9/1949 Cejka 343-901 X 2,514,167 7/1950 Scott 287-58 2,635,186 4/1953 Schmidt 343-901 X 2,864,161 12/ 1958 Curtiss 29-516 3,217,459 11/1965 Meyer 52-731 FOREIGN PATENTS 1,161,644 3/1958 France.

ELI LIEBERMAN, Primary Examiner.

US. Cl. X.R. 

6. A TELESCOPIC ANTENNA IN WHICH AT LEAST TWO ADJACENT TELESCOPIC SECTIONS EACH HAVE A PROLATE CROSS-SECTION COMPRISING A FIRST INNER SECTION HAVING A PROLATE CROSS-SECTION, A SECOND ADJACENT TUBULAR SECTION HAVING A PROLATE CROSSSECTION SUBSTANTIALLY CORRESPONDING IN CONFIGURATION TO THE CROSS-SECTION OF THE ADJACENT INNER SECTION AND TELESCOPICALLY ASSEMBLED ON SAID FIRST SECTION WITH THE AXES OF SAID CROSS-SECTIONS IN SUBSTANTIAL ALIGNMENT, A SPRING CONTACT CARRIED BY SAID FIRST SECTION AND SECURED ADJACENT THE LOWER END THEREOF, THE INNER CIRCUMFERENCE OF SAID SECOND SECTION BEING SUFFICIENTLY LARGER THAN THE OUTER CIRCUMFERENCE OF SAID FIRST SECTION TO RECEIVE SAID FIRST CARRYING SPRING CONTACT IN A COMPRESSED CONDITION, AND A FLEXIBLE PACKING RING CARRIED BY THE UPPER END OF SAID SECOND SECTION, SAID PACKING RING HAVING AN INTERNAL SURFACE IN SEALING ENGAGEMENT WITH THE SURFACE OF SAID FIRST SECTION ABOVE SAID CONTACT, AND A VISCOUS ANTI-RATTLING MATERIAL SUBSTANTIALLY FILLING THE VOID BETWEEN SAID FIRST AND SECOND SECTIONS WHEN TELESCOPED TO THE MINUMUM LENGTH OF SAID ANTENNA, WHEREBY SAID PACKING RING SEALS SAID VISCOUS MATERIAL WITHIN SAID ANTENNA AND SERVES AS A STOP LIMITING THE MAXIMUM EXTENSION OF SAID SECTIONS WITH RESPECT TO EACH OTHER, AND A MOUNTING FIXTURE CLOSING THE INTEGRAL SPACE IN SAID ANTENNA. 